Sulfur is removed from a hydrocarbon fuel via contact with a desulfurization agent; the desulfurization agent is then regenerated (wherein sulfur is released) by exposing it to oxygen. The sulfur removal and regeneration processes each can be carried out at relatively moderate temperatures, e.g., from 300 to 600.degree. C., and pressure, e.g., about 0.79 to about 3.5 MPa; and the desulfurization agent can include a transition metal oxide, such as molybdenum oxide. The process can also include the additional steps of cracking the hydrocarbon, separating high-boiling and low-boiling fractions from the reaction product and contacting the lower-boiling fraction with a secondary desulfurization agent.